Addition of hydrogen cyanide to butadiene



United States Patent O 3,547,972 ADDITION OF HYDROGEN CY ANIDE TBUTADIENE William C. Drinkard, In, Wilmington, DeL, assignor to E. I. duPont de Nemours and Company, Wilmington, Del., a corporation of DelawareNo Drawing. Filed Apr. 1, 1968, Ser. No. 717,947 Int. Cl. C07c 121/04US. Cl. 260-465;; 4 Claims ABSTRACT OF THE DISCLOSURE Hydrogen cyanidecan be added to butadiene in the presence of a hydrogen halide to givehigh yields of 3-pentenenitrile and 4-pentenenitrile, together withsmall amounts of isomeric pentenenitriles by use of a catalyst of copperchromite or activated copper chromite. The pentenenitriles can beconverted to adiponitrile, which is an intermediate for the productionof polyamides.

FIELD OF THE INVENTION This invention relates to a process of preparingpentenenitriles. More particularly this invention relates to a processof catalytically adding hydrogen cyanide to butadiene to formpentenenitriles.

DEFINITION OF THE INVENTION The process of the present invention can bedefined as a process for manufacturing pentenenitriles which comprisescontacting a mixture containing hydrogen cyanide, butadiene and ahydrogen halide wherein the halogen has an atomic number from 17 to 53with a catalyst containing copper chromite at a temperature of of 150 C.to 450 C. and recovering pentenem'triles from the reaction product.

DETAILED DESCRIPTION OF THE INVENTION The copper chromite catalystsuseful in the process of the present invention are conventional copperchromite or activated copper chromite catalysts which are well known inthe art. These catalysts can be represented by the formula:

wherein M is a metal which can be Ag, Cd, Zn, Bi, Ni(II), 0r Mn(II); Mis Mg, Ca, Sr or Ba;

n valence of M i.e., n=1 for the above metals except silver, when n=2,x, z and w are from 0.1 to 10 and generally 0.5 to 3, and y and m are 0to 10, preferably 0.2 to 2.

The promoted catalysts (where y and/or m 0) are preferred.

The catalysts are prepared by thermal decomposition of basic doubleammonium chromates, which are readily formed in aqueous medium frommetal (M") nitrates or sulfates, ammonium chromate and excess ammonia.The basic double ammonium chromates are formed as precipitates, arewashed free of soluble ammonium salts, and then calcined at 300-600 C.The following equations show the chemistry of their preparation frommetal nitrates:

After calcination the solid metal chromite/oxide mixtures are powderedand may be used in the powdered form in fluidized catalyst beds, or canbe pelleted into 3,547,972 Patented Dec. 15, 1970 granules which may beused in fixed beds. The preparation of metal chromites is described morefully by Mellow, Inorganic and Theoretical Chemistry, vol. XI, pp. 196-204, and by Adkins, Reactions of Hydrogen with Organic Compounds overCopper-Chromium Oxide and Nickel Catalysts, University of WisconsinPress, Madison, Wis., 1937, chapter II.

Hydrocynation of butadiene in the vapor phase over a copper chromitecatalyst in the presence of a hydrogen halide (other than hydrogenfluoride) can be carried out at temperatures in the range -450 C., thepreferred range being 150350 C. The pressure at which the reaction iscarried out is not critical and can range from below atmosphericpressure to at least 40 atmospheres, although a pressure of oneatmosphere or slightly above is preferred. Likewise the time of reaction(i.e., time ofi contact of the gaseous reactants and the catalyst),which will vary in the normal way with temperature and pressure, is notcritical and is generally selected for convenience and efliciency ofoperation.

The proportion of butadiene and hydrogen cyanide in the process ispreferably from about 10:1 to about 1:10 in butadiene2HCN molar (gasvolume) ratio, the most preferred ratio being 1:1. An excess ofbutadiene is undesirable because it can undergo a side reaction to formvinylcyclohexene under the conditions of the process. The amount ofhydrogen halide in the butadiene gas stream is preferably from about1:50 to 1:1 in HCl:butadiene volume ratio, the most preferred ratiobeing about 1:10. An inert carrier gas such as nitrogen or helium can beused but is not necessary.

The addition of HCN to butadiene can result in the following products:cis and trans 2-methyl-2-butenenitrile (2M2BN), 2-methyl-3-butenenitrile(2M3BN); cis and trans Z-pentenenitrile (2PN), cis and trans3-pentenenitrile (3PN) and 4-pentenenitrile (4PN). Of these products,3PN and 4PN are particularly valuable since they can be converteddirectly to adiponitrile, a valuable nylon intermediate, by suchprocesses as those disclosed by W. C. Drinkard, Jr. in US. applicationSer. No. 697,564, filed Oct. 31, 1967. Thus 3- and 4-pentenenitriles canbe reacted with hydrogen cyanide in the presence of a catalyst ofzero-valent nickel complexed with a trihydrocarbyl phosphite and analkali metal borohydride at a temperature between 25 and 200 C., toyield adiponitrile.

This invention is further illustrated by the following specificexamples, which are not, however intended to fully delineate the scopeof the present discovery.

EXAMPLES 1-3 Vapor phase hydrocyanations of butadiene were carried outin a vertical Pyrex glass column 18" long by 1.5 cm. diameter and heatedby a 12" heating band. A 6 mm. O.D. thermowell extended to the bottom ofthe catalyst section and contained a thermocouple positioned at themidpoint of catalyst depth, which was 9 inches overall, centered insidethe heating band. Catalyst was supported by a fritted glass disk at thebottom of the catalyst section. Fitted to the top of the reactor columnby a 28/15 glass join was a head containing a gas inlet tube fornitrogen purge or reagent feed and a safety blowoff through a pool ofmercury set for a maximum pressure of /z-atrnosphere above roompressure. Fritted to the bottom of the column by a 19/22 glass joint wasa water cooled condenser and vented flask for condensation andcollection of liquid product.

The reagent gases were mixed before being fed to the reactor column. Aslow stream of nitrogen carrier gas was bubbled through liquid hydrogencyanide at 25 C. and then mixed with the butadiene-hydrogen chloridemixture, which entered by means of a T-joint. Hydrogen chloride gas wasintroduced into the butadiene stream via a hypodermic needle insertedthrough the wall of the rubber delivery tube attached to the butadienesource. Individual flow rates were observed and regulated by bubblerates in appropriately located small traps containing of 2 g. perminute. A sample of the supernatant liquid Was tested with aqueousammonia and the mixture became cloudy. More gaseous NH was added to thereaction mixture until a test with aqueous ammonia showed thatprecipitation was complete. The precipitate was filtered,

inert liquid. 5 washed and dried at 150 C., then calcined at 450 C. Thereactor column was charged with 45 ml. of catalyst for 3 hours. A 100 g.portion of the calcined powder was and the equipment assembled asdescribed above. The Syskneaded into a paste with a solution comprising30 cc. tern was purged with nitrogen and the catalyst heated to of H 0,2.71 g. of C and 1.1 g. of MgO. The paste about 200 C. (200:) asmeasured at the mid-point 10 Was dried at 150 C., crushed and screenedto 100% of catalyst depth. A mixture of nitrogen, butadiene, hythrough a10 mesh screen, mixed with graphite (1%), drogen cyanide and hydrogenchloride (volume ratio and pressed into 7 long by diameter pellets. The1:1:l:0.1) was then passed over the catalyst. Temperapellets werefinally calcined at 600 C. for 3 hours. The ture changes were observedand the run was terminated composition was [CuCr O -CuO]0.172[MgCrOMgO]. when there was evidence of cessation of exothermic re- 1 EXAMPLE 3action. Liquid product collected at 25 C. was analyzed 0 by gaschromatography with a chromatographic column copper-nlckel-llnc-baflllmchfomlte previously calibrated for analysis of mixtures of Z-methyl-This catalyst was prepared as described by Reeves and 2-butenenitrile,2-methyl-3-butenenitrile, Z-pentenemtrile, Adkins J' Am h 2 2374 (194The 3-pentenenitrile, and 4-pentenenitrile. 20 position was Table Isummarizes the results obtained with various copper chromite catalysts,using the procedure described [cuCr2O4'CuO] 2 4 Cr O -ZnO] above.0.33[BaCrO -BaO] The catalysts used in the foregoing examples were pre-As many apparently widely different embodiments of pared by thefollowing procedures. this invention may be made without departing fromthe TABLE 1 Pentenenitriles in crude product, percent 2M2BN 3PN ChromiteTemp, Time, Product catalyst C. min. vol.,ml. Cis Trans 2M3BN/c2PN t-2PNC15 Trans 4PN Example:

1 Cu-Zn 213-339 25 4.2 2.2 11.4 2 5 16.9 41.7 11.0 Cu-Mg 208-220 3 8.511.1 70. Cui-Zn-Ba 194-312 44 5 1.4 .1 8.5 1 7 12.2 56.1 4.8

NOTES! (1) The crude products also contained minor proportions ofbenzene an (2) 2M3BN and cis-2PN are not separated by the gaschromatographic 0 Gaseous NH (165 grams) was introduced at a rate of 3.5g. per minute into a stirred aqueous solution containing 570 g. of ZnSO-5H O, 283 g. of CuSO -5H O and 355 g. of CrO in a total volume of 6liters at 38 C. When precipitation was complete, agitation was stoppedand the precipitate was washed with distilled water by repeateddecantations to remove sulfate ions. When the concentration of sulfateions in the supernatant liquid was reduced at less than 2% by analysis,the clear liquid was decanted to the lowest level possible without lossof precipitate. The precipitate was then redissolved in the remainingwater by adding 550 grams of CrO gradually with stirring. The solutionwas diluted to 6 liters at 38 C., and gaseous NH again added withstirring as before to effect complete reprecipitation. The precipitatewas again washed by decantation until the sulfate content of the motherliquor was less than 10 p.p.m. The sulfatefree precipitate was filtered,dried and calcined at 480 C. for 2 hours. The calcined solid wasdensified by compression as a wet paste in a heavy duty kneader, andthen was redried, crushed and screened to through a 10 mesh screen. Theresulting powder was mixed with graphite (1%) and formed into pelletslong by diameter in a pilling machine. The pellets were finally calcinedat 500 C. for 3 hours. The composition was [CuCr O CuO] 2 [ZnC'r O ZnO].

EXAMPLE 2 Copper-magnesium chromite CrO (400 g.) was added gradually toa stirred solution of 752 g. of Cu(NO in 6 liters of water at roomtemperature. The resulting solution was adjusted to 30 C., and then 180g. of gaseous NH was added at the rate d vinylcyelhhexene.

olumn used in these analyses.

spirit and scope thereof, it is to be understood that this invention isnot limited to the specific embodiments thereof except as defined in theappended claims.

The embodiments of this invention in which an exclusive property orprivilege is claimed are defined as follows: 1. A process for themanufacture of pentenenitriles by addition of hydrogen cyanide tobutadine which comprises contacting a mixture comprising hydrogencyanide, butadiene and a hydrogen halide wherein the halogen has anatomic number of from 17 to 5 3 with a catalyst having the formula:

[CuCr O -x- CuO] M Cr O -zM O] m [M'CrO wMO] wherein:

M is Ag, Cd, Zn, Bi, Ni(II) or Mn(II) M is Mg, Ca, Sr or Ba 2 n 13valence of M x, z and w are from 0.1 to 10; and m and y are from 0 to 10at a temperature of from to 450 C.

2. The process of claim 1 in which said catalyst is copper zincchromite.

3. The process of claim 1 in which said catalyst is copper magnesiumchromite.

4. The process of claim 1 in which said catalyst iscopper-nickel-zinc-barium chromite.

References Cited UNITED STATES PATENTS 2,402,873 6/1946 Coffman et a1.260-4653 JOSEPH P. BRUST, Primary Examiner U.S. Cl. X.R.

P0405) UNITED STATES PATENT OFFICE l 69 CERTIFICATE OF CORRECTION PatentNo. 3 5 4 912 Dated December- 15, 1970 Invento C. Drinkard, JI'.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 2, line 2, "Mellow" should be Mellor- Column 2, line 61 "Join"should be Joint Column 2, line 6 "Fritted" should be Fitted Table 1,Note (1), "vinylcycl9hexene" should be vinylcyclohexene Column 4 line H!"butadine" should be butadiene Column 4 line 19, that portion of theformula "CuO]M Cr 0 should be --CuO]y[M C1" Signed and sealed this 20thday of April 1971 (SEAL) Attest:

EDWARD M.FLET( IHER,JR. WILLIAM E. SCHUYLER, JR. Attesting OfflCBICommissioner of Patents

